Reproduction mastering without hormones in small ruminants

Abstract

Reproduction mastering in sheep and goat farms is important for out-of-season breeding, births grouping and artificial insemination (AI) performing. The use of hormones to induce and synchronise oestrus and ovulations is the most effective way to achieve these goals. The use of photoperiodic treatments and/or the male effect appears as an alternative solution to limit the use of hormones in small ruminants breeding. This article discusses about the specificities of the ovulatory and behavioural response of females to the "male effect", as well as the physiological bases that contribute to the success of this practice in sheep and goat. Pre-treatment of animals with photoperiodic strategies is required so that the male effect is successful, especially in highly seasonal breeds such as the Alpine and Saanen goat breeds. Light treatments are currently available for reproduction by male effect in any season, but the use of melatonin is necessary at some periods of the year. New light treatments without melatonin are currently under study. AI protocols using male effect are emerging. Some of them combine the male effect with progestagens and/or prostaglandins, and allow a single AI at a predetermined time. Hormone-free AI protocols based on the male effect are also available. In goats, these protocols include 1 or 2 AI times, with or without previous heat detection. In sheep, heat detection is mandatory for AI following ram effect without the use of hormones. In both species, the development of automated heat detection methods will facilitate the deployment of hormone-free AI protocols.